The invention relates to a device and a method for electrographic printing or copying by using liquid ink. Further, the invention relates to an applicator element, a cleaning station and a regeneration station, each of which is adapted to the use of liquid ink.
Known devices for electrographic printing or copying make use of a process in which dry toner is applied to the latent image of a latent image carrier, for example a photoconductor. Such dry toner results in relatively thick toner layers since the toner particles have a relatively large particle size and a plurality of toner particles have to be deposited on top of each other for achieving sufficient color coverage. The dry toner layer applied to the latent image has to be fixed, this requiring a relatively high energy. This high energy leads to a high stress on the final image carrier, preferably paper, as a result of the fixing by means of heat and/or pressure.
Liquid toners that have been used up to now contain a carrier liquid that is odorous and inflammable. Often, the final image carrier to which the liquid toner is applied is likewise odorous. When liquid toner is used, it is brought into contact with the latent image carrier.
U.S. Pat. No. 5,943,535 discloses the use of a water-based liquid toner that is brought into contact with the latent image carrier. Owing to the conductive liquid toner, a deposit corresponding to the electrostatic charge image is formed on the latent image carrier.
DE-A-30 00 019 which corresponds to U.S. Pat. No. 4,268,597 discloses a device for a liquid developer. A latent image, for example a potential pattern, is generated on the final image carrier. An applicator element carries a liquid layer. An air gap having a predetermined air gap width is set between the liquid layer and the final image carrier. Liquid elements of the liquid layer are transferred onto the surface of the final image carrier due to its electric potential.
U.S. Pat. No. 4,982,692 discloses a method for printing that uses a liquid developer. Under effect of an electrostatic force field, droplets of a liquid layer on an applicator element are transferred onto the surface of a latent image carrier.
Further, U.S. Pat. No. 5,622,805 discloses a method using a liquid developer in which method droplets on an applicator roller are transferred onto the surface of a latent image carrier under influence of an electrostatic field.
Furthermore, reference has to be made to conventional printing methods, such as offset printing, which use liquid ink. With these conventional printing methods, the print form is not variable so that economical printing of small numbers of copies is not possible.